The invention relates to a dishwasher with an energy-saving heating mode and a method for operating such a dishwasher.
In conventional dishwashers, a washing liquid, usually called a washing solution, is heated during individual sub-program steps, e.g., “cleaning” and “rinsing” and the washing solution wets the dishes located in the dishwasher by means of a spraying system provided, for example, spray arms. As a result of the continuous circulation and action of the washing solution on the dishes and uniform heating of the washing solution, not only the washing solution is heated but also the dishes to be cleaned and the washing container and the materials arranged directly adjacent thereto, for example, insulating material.
In order to finally heat a washing solution to a specific temperature provided by the washing program, a total amount of energy which takes into account the heating of the dishes and the washing container in addition to the washing solution must be expended.
For example, at the beginning of the cleaning phase, a first partial quantity of the washing solution is heated to a temperature, for example 65° C. and guided onto the dishes by means of the spraying system. As a result of the lower temperature of the dishes of about 20 to 24° C., the first partial quantity of the washing solution delivers a certain quantity of heat to the dishes so that the temperature of the dishes increases but the temperature of the washing solution decreases. The partial quantity of the washing solution thus cooled flows back via the circulating pump and is further heated until a specific temperature is reached. As a result of this continuous process, both the dishes and also areas of the washing container are heated to this predetermined temperature before the desired washing solution temperature is reached.
However, since only the temperature of the washing solution is important for achieving the desired cleaning performance, the energy balance of the dishwasher is disadvantageously influenced by the heating of the dishes and the washing container.